1. Field of the Invention
The present invention relates to a method used in a communication system and related communication device, and more particularly, to a method of transferring ownership of a service group in a communication system and related communication device.
2. Description of the Prior Art
The Open Mobile Alliance (OMA) is founded to develop OMA specifications for mobile services to meet users' needs. Furthermore, the OMA specifications aim to provide the mobile services which are interoperable across geographic areas (e.g. countries), operators, service providers, networks, operation systems and mobile devices. In detail, the mobile services conforming to the OMA specifications can be used by the users without restriction to particular operators and service providers. The mobile services conforming to the OMA specifications are also bearer agnostic, i.e., the bearer that carries the mobile services can be a second generation (2G) mobile system such as GSM, EDGE or GPRS, or a third generation (3G) and beyond mobile system such as UMTS, LTE or LTE-Advanced. Further, the mobile services can be executed on an operation system such as Windows, Android or Linux operated on various mobile devices. Therefore, industries providing devices or the mobile services supporting the OMA specifications can benefit from a largely growing market enabled by interoperability of the mobile services. Besides, the users use the devices or the mobile services supporting the OMA specifications can also have a better experience due to the interoperability of the mobile services.
Furthermore, Converged Personal Network Services (CPNS) is developed by the OMA to provide application-layer support for ubiquitous access to services in a converged network, which is a group of Personal Networks (PNs) that are interconnected by PN Gateways (PN GWs). In detail, an architecture of the CPNS includes three entities which are a CPNS server, a PN GW, and one or more PN elements (PNEs). The CPNS server receives requests from the PN GW, and replies responses to the PN GW, to ensure that appropriate applications are selected and appropriate contents are provided to the PNEs via the PN GW. The PN GW serves as an intermediary entity between the PNEs and other networks that forwards the requests and the responses between the PNEs and the other networks. The PN GW can be a mobile phone, or an IP-enabled set-top box. Besides, the PNEs are PN entities that are connected to the PN GW and between each other, and are used for rendering the content received from the PN GW or from each other. The PNE can be a mobile phone, a personal computer (PC), a music player, a car navigation system or an IP-enabled set-top box. For example, a PN GW can be a mobile phone which integrates a Bluetooth network and a cellular network. In this situation, a PNE which is a Personal Media Player (PMP) connected to the Bluetooth network can receive video contents from the Internet via the mobile phone connected to the cellular network.
On the other hand, the OMA develops a concept of service group (SG) for the CPNS. The SG is composed of one or more PN GWs and one or more PNEs, which are necessary for the SG to operate normally. The intention of the service group is to group together PNEs which want to receive the same service from a CPNS server or a content provider. In other words, for those PNEs that want to receive a game service can belong to a SG receiving the game service, and for those PNEs that want to receive a music service can belong to a SG receiving the music service. Besides, a PNE creating a SG is assigned as a SG Owner. The SG owner possesses ownership of the SG for managing the SG by inviting a new SG member, expelling a SG member, deleting the SG, etc. Further, a PNE belonging to the SG can leave the SG or abandons to be the owner by sending a SG Leave Request to a corresponding CPNS server via a PN GW managing the PNE. However, when the SG owner leaves the SG or abandons to be the owner, the SG cannot be managed by any other PNEs without the ownership of the SG. The SG will no longer operate normally. Therefore, how to handle the problem when the SG owner intends to leave the SG is a topic to be discussed and addressed.